This invention relates to an apparatus for supplying a flux and torque command to an electric vehicle drive system having as an input vehicle accelerator pedal position.
One of the many criteria in the design of electric vehicle drive systems is that the electric vehicle drive system approximate the driving chacteristics of the conventional internal combustion automobile. Specifically, the electric vehicle drive system must be capable providing smooth vehicle acceleration and deceleration in accordance with driver commands supplied to the vehicle drive system through the accelerator pedal.
Another criteria in the design of electric vehicle drive systems is that such a drive system be rugged so as not to require frequent maintenance. Further, such vehicle drive systems must be efficient to maximize vehicle range.
Configuring the electric vehicle drive system from an inverter-induction machine drive allows a rugged and efficient electric vehicle drive system to be realized. However, the inverter-induction machine drive, when controlled by conventional techniques such as torque regulation and using an optimum size inverter, exhibits a dead zone at high speeds because of the inability of the inverter-induction machine drive to supply constant torque.
It is an object of the present invention to provide an electric vehicle drive system which achieves smooth control of vehicle acceleration and deceleration at all speeds.
It is another object of the present invention to provide a balancing speed characteristic as a function of accelerator pedal position for driving at a constant speed.
It is still another object of the present invention to provide an electric vehicle drive system, responsive to operator commands as transmitted through the vehicle accelerator pedal, which approximates the driving characteristics of an internal combustion engine automobile.